/*-
 * ============LICENSE_START=======================================================
 * dmaap-kafka-client
 * ================================================================================
 * Copyright (C) 2023 Nordix Foundation. All rights reserved.
 * ================================================================================
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 * ============LICENSE_END=========================================================
 */

package org.onap.dmaap.kafka;

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.UUID;
import org.apache.kafka.clients.CommonClientConfigs;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.config.SaslConfigs;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Utility class that provides a KafkaConsumer to communicate with a kafka cluster
 */
public class OnapKafkaConsumer {

    private final Logger log = LoggerFactory.getLogger(OnapKafkaConsumer.class);
    private final KafkaConsumer<String, String> consumer;
    private final int pollTimeout;
    private final List<String> consumerTopics;

    /**
     *
     * @param configuration The config provided to the client
     */
    public OnapKafkaConsumer(IKafkaConfig configuration) {
        consumerTopics = configuration.getConsumerTopics();
        log.debug("Instantiating kafka consumer for topics {}", consumerTopics);

        Properties props = new Properties();
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,  "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.CLIENT_ID_CONFIG, configuration.getConsumerID() + "-consumer-" + UUID.randomUUID());
        props.put(CommonClientConfigs.SECURITY_PROTOCOL_CONFIG, configuration.getKafkaSecurityProtocolConfig());
        props.put(CommonClientConfigs.BOOTSTRAP_SERVERS_CONFIG, configuration.getKafkaBootstrapServers());
        props.put(SaslConfigs.SASL_JAAS_CONFIG, configuration.getKafkaSaslJaasConfig());
        props.put(SaslConfigs.SASL_MECHANISM, configuration.getKafkaSaslMechanism());
        props.put(ConsumerConfig.GROUP_ID_CONFIG, configuration.getConsumerGroup());
        props.put(ConsumerConfig.ALLOW_AUTO_CREATE_TOPICS_CONFIG, false);
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);

        consumer = new KafkaConsumer<>(props);

        pollTimeout = configuration.getPollingTimeout();
    }

    /**
     *  Poll specified topic for existing messages
     *
     * @return List of messages from a specific topic
     */
    List<String> poll(String topicName) throws KafkaException {
        List<String> msgs = new ArrayList<>();
        log.debug("Polling records for topic {}", topicName);
        ConsumerRecords<String, String> consumerRecordsForSpecificTopic = consumer.poll(Duration.ofSeconds(pollTimeout));
        for(ConsumerRecord<String, String> rec : consumerRecordsForSpecificTopic){
            if (rec.topic().equals(topicName)) {
                msgs.add(rec.value());
            }
        }
        return msgs;
    }

    /**
     *  Poll topics for existing messages
     *
     * @return List of messages from all subscribed topic
     */
    List<String> poll() throws KafkaException {
        List<String> msgs = new ArrayList<>();
        log.debug("Polling all records");
        ConsumerRecords<String, String> consumerRecords = consumer.poll(Duration.ofSeconds(pollTimeout));
        for(ConsumerRecord<String, String> rec : consumerRecords){
            msgs.add(rec.value());
        }
        return msgs;
    }

    public void subscribeConsumerToTopics() {
        try {
            consumer.subscribe(consumerTopics);
        }
        catch (KafkaException e) {
            log.error("Failed to subscribe to given topic(s) {} : {}", consumerTopics, e.getMessage());
            throw e;
        }
    }
}